java数字签名算法之RSA

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实例

1.项目结构

2.pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">

  	<modelVersion>4.0.0</modelVersion>

	<groupId>org.security</groupId>
	<artifactId>DigitalSignature</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>jar</packaging>

	<properties>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
	</properties>

	<dependencies>
		<!-- junit -->
		<dependency>
			<groupId>junit</groupId>
			<artifactId>junit</artifactId>
			<version>4.12</version>
			<scope>test</scope>
		</dependency>
		<!-- commons-codec -->
		<dependency>
		    <groupId>commons-codec</groupId>
		    <artifactId>commons-codec</artifactId>
		    <version>1.10</version>
		</dependency>
	</dependencies>
</project>

3.RSA.java

package org.security.rsa;

import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.Signature;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;

import org.apache.commons.codec.binary.Base64;

public class RSA {

	private static final String str = "Digital signature algorithm RSA MD5WithRSA";

	private static final String SECURITY = "RSA";// 加密方式
	private static final String ALGORITHM = "MD5withRSA";// 加密算法
	private static final String PUBLIC_KEY = "RSAPublicKey";// 公钥
	private static final String PRIVATE_KEY = "RSAPrivateKey";// 秘钥

	public static void main(String[] args) {

		System.out.println("==========初始化密钥信息==========");
		Map<String, Object> map = RSA.init();
		System.out.println("=========密钥信息初始化成功=========");
		byte[] private_key = RSA.getPrivateKey(map);
		System.out.println("=============私钥为=============\n" + Base64.encodeBase64String(private_key));
		byte[] public_key = RSA.getPublicKey(map);
		System.out.println("=============公钥为=============\n" + Base64.encodeBase64String(public_key));
		byte[] bs = RSA.sign(private_key);
		System.out.println("=============签名为=============\n" + Base64.encodeBase64String(bs));
		boolean result = RSA.verify(public_key, bs);
		System.out.println("===========签名验证结果===========\n" + result);

	}

	/**
	 * 初始化密钥
	 *
	 * @return
	 */
	private static Map<String, Object> init() {

		Map<String, Object> map = null;
		try {
			// 生成实现指定算法的KeyPairGenerator对象，用于生成密钥对
			KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance(SECURITY);
			keyPairGenerator.initialize(1024);// 初始化密钥长度
			KeyPair keyPair = keyPairGenerator.generateKeyPair();// 生成密钥对
			RSAPublicKey rsaPublicKey = (RSAPublicKey) keyPair.getPublic();// 获取公钥
			RSAPrivateKey rsaPrivateKey = (RSAPrivateKey) keyPair.getPrivate();// 获取私钥

			// 保存到map中
			map = new HashMap<String, Object>();
			map.put(PUBLIC_KEY, rsaPublicKey);
			map.put(PRIVATE_KEY, rsaPrivateKey);
		} catch (Exception e) {
			e.printStackTrace();
		}
		return map;

	}

	/**
	 * 用私钥生成签名
	 *
	 * @param privateKey
	 * 						私钥字节数组
	 * @return
	 */
	private static byte[] sign(byte[] privateKey) {

		byte[] signByte = null;
		try {
			// 根据给定的编码密钥创建一个新的PKCS8EncodedKeySpec对象，指定PKCS#8标准为密钥规范管理的编码格式
			PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(privateKey);
			// 实例化密钥工厂对象，将密钥转换成密钥规范
			KeyFactory keyFactory = KeyFactory.getInstance(SECURITY);
			// 根据提供的密钥规范生成私钥对象
			PrivateKey key = keyFactory.generatePrivate(pkcs8EncodedKeySpec);
			// 实例化实现指定签名算法的Signature对象
			Signature signature = Signature.getInstance(ALGORITHM);
			// 根据私钥对象初始化签名对象
			signature.initSign(key);
			// 使用指定的byte数组更新要签名或验证的数据
			signature.update(str.getBytes());
			// 返回所有已更新数据的签名字节
			signByte = signature.sign();
		} catch (Exception e) {
			e.printStackTrace();
		}
		return signByte;

	}

	/**
	 * 用公钥验证签名
	 *
	 * @param publicKey
	 * 					公钥字节数组
	 * @param signByte
	 * 					签名字节数组
	 * @return
	 */
	public static boolean verify(byte[] publicKey, byte[] signByte) {

		boolean result = false;
		try {
			// 根据给定的编码密钥创建一个新的X509EncodedKeySpec对象
			X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(publicKey);
			// 实例化密钥工厂对象，将密钥转换成密钥规范
			KeyFactory keyFactory = KeyFactory.getInstance(SECURITY);
			// 根据提供的密钥规范生成公钥对象
			PublicKey key = keyFactory.generatePublic(x509EncodedKeySpec);
			// 实例化实现指定签名算法的Signature对象
			Signature signature = Signature.getInstance(ALGORITHM);
			// 根据公钥对象初始化用于验证的对象
			signature.initVerify(key);
			// 使用指定的byte数组更新要签名或验证的数据
			signature.update(str.getBytes());
			// 验证传入的签名
			result = signature.verify(signByte);
		} catch (Exception e) {
			e.printStackTrace();
		}
		return result;

	}

	/**
	 * 获取私钥
	 *
	 * @param map
	 * 				密钥map集合
	 * @return
	 */
	public static byte[] getPrivateKey(Map<String, Object> map) {

		RSAPrivateKey key = (RSAPrivateKey) map.get(PRIVATE_KEY);
		return key.getEncoded();

	}

	/**
	 * 获取私钥
	 *
	 * @param map
	 * 				密钥map集合
	 * @return
	 */
	public static byte[] getPublicKey(Map<String, Object> map) {

		RSAPublicKey key = (RSAPublicKey) map.get(PUBLIC_KEY);
		return key.getEncoded();

	}

}

4.效果预览

==========初始化密钥信息==========
=========密钥信息初始化成功=========
=============私钥为=============
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
=============公钥为=============
MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCLG6V1r9Yyf/LCzTwvXVqgZl4csezBU918MsWPbjtZiya9W4i9ocrWPqxXhi/hAocZZwkkuB/DNe31T+54eSpORT+7E6qd4XsKfTy6ShbMrT+U97q0GG0OULSrx+KGlJOFLvCCdQXNHEzb8XkrpbzDM8ZPsLlRHcXzt7QS1Fpo3QIDAQAB
=============签名为=============
ODGCnrrBV/1SXfB65SHYWbdgNAuY8QbfAzWGeRscMhGCudfQk9cnLzHVQkhlC9eXruTvjQqQSmBNLmGdegUlAh+bPi/EkqReidD0efsLSy4FQSJIdmFVW6Xl3FuAqzIqidPLPFk0rFDK/DJzGVQtUYm5rKDap0zKMxe/P3/6bbs=
===========签名验证结果===========
true

参考：http://www.imooc.com/video/6154